Abstract: A semiconductor memory device having first and second memory architectures with different structures and allowing the possibility of selecting any one of the first and second memory architectures using a selection process and a memory system using the semiconductor memory device are provided. The first memory architecture has p banks, a page size of m/2 bytes of m/2 memory cells connected to one word line in each of the banks, and n/2 data terminals DQ. The second memory architecture has p banks, a page size of m bytes, and n data terminals. The option process may be realized by a bonding, a mask pattern, or a fuse. In a memory device, the page size and the number of memory banks are adjusted by a design option. Thus, the memory architecture is modified, redundancy flexibility is increased and power consumption is reduced.